Wood-sttbfaciua machine



. Oct. 22, 1929; .A. A. CLARKE I woon sunmcme momma Filed April 10. 1926 4 Sheets-Sheeli 1 Oct. 22, 1929. CLARKE 1,732,594

WOOD SURFACING MACHINE Filed April 10, 1926 4 Sheets-Sheet 2 ZZZ 2 9- A. A. CLARKE 1 r I 1,732,594

' WOOD SURFACING' MACHINE Filed April 10, 1926 4 Sheets-Sheet 4 IH u i. g it I f: m i": MM 7 f Wmml I Hg I Patented Oct. 22, 1929 UNITEB ALEX A. CLARKE, OF CHICAGO, ILLINOIS WOOD-SUBFACING MACHINE Application filed. April 10,

This invention relates to apparatus for the surface smoothing or finishing of woodwork andthe like by abrasion, such as by sandpapering. It has to do particularly with a machine specially qualified for bench work,

although not limited for its utility to such employment.

The general object of the invention is the provision of an efficient surface finishing or abrading machine of very compact construction and light weight, whereby it is specially qualified for employment as a hand manipulated bench tool susceptible of use by a workman with accuracy and without inconvenient physical exertion. The attainment of this object imposes limitations on the weight of the machine as well as upon its size, such as will permit itsbeing handled with accuracy and with a minimum of physical exertion, and at the same time necessitates provision for adequate power requirements and a high cutting or abrading rate. The proper cooling of the motor and the abrading element, and the convenient disposal of dust also are factors of great importance in the utility of the machine.

Included among the more particular objects of the invention, therefore, are the following: The provision of a construction wherein all'working parts are effectively housed and protected fromvinterference from the clothing or the person of the operator or other external articles;

f Improved organization of the machine for facilitating adjustmentof the operating drum relative to the work during operation; Improved organization of the drum mounting and driving mechanism, permitting adjustment of the drum for alignment of its operating surface with tl1 WO1k, Wh8I1 desired; 1 e

A novel mounting arrangement for the machine whereby it may be operated conveniently and accurately for floor smoothin 1926. Serial No. 101,033.

with the working pressure constantly under the control of the operator.

Other and further objects'of the invention will be pointed out hereinafter, indicated in the appended claims, or obvious to one skilledin the art upon an understanding of the invention from the present disclosure.

For the purpose of this application, I have shown herein one form of apparatus embodying the invention, but it is to be under-- stood that the same is presented for illustration only and is not to be accorded any interpretation having the effect of limiting the invention set out in the appended claims, short of its true and most comprehensive scope in the art.

In the drawingsforming a part ofthis specification,

Fig. 1 is a top view of a sanding machine without the dust sack;

Fig. 2 is a left-hand side elevational View;

Fig. 3 is a sectional viewon substantially line 33 of Fig. 2, showing most of'the'casing portion of the machine in elevation;

Fig. 4 is a longitudinal sectional view on substantially line 4-4 of Figs. 1 and 3 I Fig. 5-is a transverse sectional view on substantially line 55 of Fig. 2;

Fig. 6 is a longitudinal sectional "view on substantially line 66 of Fig. 1; 7

-Fig. I IS an elevational detail taken at th point indicated at 7 -7 on Fig. 5; r

Fig. 8 is a sectional plan -view on theline 88,'Fig. 7; I v

Fig. 9 is a top view showing the machine mounted for floor work, and a Fig. 10 is a side elevational view of the same. 1 Described generally, my invention comprises the novel organization-of an operating drum, suitable forcarryingsandpaperorother desired surfacing material, and a motor for actuating the drum, said parts being suitably housed in acasing adapted to present the working parts in proper relationshipto' the surface to be acted upon by the surfacing mawithout inappropriate exertion on the part of the operator, as a hand-tool for bench work. Novel features in the organization which accomplish this result involve the provision of an operating drum of small diameter and a high speed motor operably connected with the drum in such fashion as to drive thesame with a peripheral speed, preferably 3110 linear feet per minute under average working conditions. Instead of relying on the weight" or pressure or extensive contact between the abrading material and the work, to secure the desired cutting or abrading elf eet on the latter, my invention contemplates a relatively small area of contact, very limited pressure, and a relatively high rate of movement of the abrading element. In these features it differs fundamentally from the construction of wood sanding machines heretofore most extensively'sl otted at 11- to provide an aperture in which the abrading element operates. The base member includes the upstanding lateral flanges 12 and the transverse reinforcing flanges 14, in associationwith certain which are formed the bosses 15 for attachmentiof the carriage, in the manner hereinafter described. The base-member also 1S formed wlth the upstand ng lugs 16 which i constitute the mountings forjthecasing, and

a; lug 17 to which is pivotally connected the casing adjusting screw 18. The casing, whichj hashinged connection with the base frame 10 by means of its hinge lugs 1.9 and pintles. 20, is subdivided into a number of housings for the various operating parts. its ower. part 2lx nnsa. ousing; for the drum, said housing, being open at the bottom inja position overthe base slot 11. An arcuate partition '22-, separates the drum housing from thefmotor housingf24, which positioned above the drum housing, and has an Open Side in which is' mounted the motor frame. plate, 25. At the front of the drum housing is formed thesuction duct 26, having its inlet: 26" at the lower edge 'ofthe casing, This. duct extendsnp ovorthe front of the drum-housing, in the form shown in =1 Eig. 3,with a gradual change from the slotlike dimensions of the inlet to a narrower and deeper formof conduit, which turns laterally at 26 and then continues upwardly at 26 partly across the end of the motor housing where it terminates in a port 26 com municating with a fan compartment 27. The outer side of the fan compartment is closed by the gear housing 28, which is fitted at its outer side with a cover plate 29. At

its front side, the fan housing is provided with the dust outlet 27 At the middle of the front and rear sides of the casing are provided the handle seats 30 in which are mounted the handle yokes 31. In one of the yokes is mounted the handle 32 having the switch housing 34 formed at the upper endthereof. and enclosing a switch which is operated by the lever 35 to control the supply of eurrent through the cable 36. In the other handle yoke is rotatably mounted the adjusting handle. 37, the lower portion of which is formed for screw-thread engagement with the adjusting screw 18. By rotation of the handle 37, therefore, the easing may be swung on the pintles 20 to vary the elevation ofv the parts carriedin the casing relative to the base. A flexible apron 38 is attached to the front of the casing, extending across the same and bearing. at its lower edge on the upper surfaceof thebase, said apron accommodating the adjustment of the casing. v

Bushings 39 and 40 are mounted in the side walls of the drum housingand carry the drum arbor 41, on which are supported the roller bearings 42, which carrythe drum The drum isa hollowcylindricaLmemher, slightly ehamfered at its ends, and having the end flanges 44 which carry the hub portions. 45 in which the roller bearings are mounted. A tube 46. is supported between the hub portions as a lubricant housing for the bearings 42, which tube prevents access of dust tothe bearings from the inside of the drum, while they are similarly protected at the outside by the packing gaskets, 4'1 The drum is provided with a diagonal groove 47 in its face, in which is mounted a clamping strip 48 which may. vbe drawn up by. screws 48?. thatv interanchor bush.- ings 48 havingscrewthreaded engagement with bosses 48 in the drum. 44, whereby to clamp the sandpaper on the peripheryof the drum. A pinion 49 having spiral teeth is securedfcoaxially to one ofthe hub mem- ,The eu t nei f e ar er i n the bushing 40 is eccentric of the latter, and the bushing may be rotated in, itsmounting in the casing'lwall by means iof a spanner engaged in the spanner holes 40 2' Inthis fashion the adjacent end of-the drum' may be raised and lowered so as to obtain thede sired bearing of the sandpaper. against the work throughout. the length ofth'e drum,

desired adjustment. *The periphery of the drum is covered with a layer of compressible material 50, such as felt, upon which the sandpaper 51 is tightly constricted by the clamping strip 48.

\Vithin the motor housing 24 are mounted the field elements 52 and commutator brushes 54 of a high speed motor of the universal type, the armature 55 and commutator 56 of whichare carried on the rotor shaft 57. This shaft is carried at one end in the ball-bearing 58 supported in the cover plate 25, and at the other end in the bearing 59 carried in the gear housing 28, and extends through the air duct 26 and the fan housing 27 In the latter is the centrifugal fan 60, mounted on the armature shaft 57. The fan housing and exhaust duct 26 have communication with the motor housing through the opening 54* in the side wall of the latter. On the end of the armature shaft, and housed by the gear casing 28 and cover plate 29, is a spiral-tooth pinion 61 which meshes with a similar pinion 62 that is carried on the bearing 64 mounted on,

' a stud 65 in the gear casing 28. The pinion 62 mesheswith a spiral-tooth pinion 66 which isfixed to a short counter-shaft 67 one end of which is j ournalled in a ball-bearing 68 carried by'the gear case cover 29. The other end u of said shaft 67 is journalled in a ball-bearing 69 supported in the gear casing. The last mentioned bearing is of double-row construction and takes up the thrust both endwise and radial, imposed on the shaft 67 At its inner end the stubshaft 67 carries the pinion 70 which meshes with the pinion 49 ,securedto the drum. Through this chain of gearing the drum is drivenby the motor in. a direction which is clockwise when viewed in the posi tion illustrated in Figs. 4 and 6, in which operation, it will be observed the dust is thrown from the sandpaper toward the apron.

38 and intake 26 of the exhaust duct which is close to the periphery of the drum where it leaves the-work.

The motor is of the series-wound universal type designed to be employed with either alternating'or direct current, and to develop approximately one-half horsepower. The drum 44; is of relatively small diameter, so as to permit the sandpaper to have only a very limited degree of contact with the work. For example, with a drum having a diameter of approximately four and one quarter inches theextent of peripheral contact of the sandpaper with the workwill be only aboutto 3 g ofa'n'inch under working conditions. At a drum length of about one and one halfof the drum diameter and the usual weight of such tools of lessthan 50 pounds the sanding druni will be applied against the-treated surface with a pressure of less than nine pounds per inch of cutting length, the pressure being in general of the order of about 4 pounds per inch cutting length. With these characteristics of the motor, drum and driving connections, the drum will be driven at a speed per minute under the average working conditions, the motor being energized from the usual lighting circuit carrying a constant pressure of approximately volts. As stated, this represents the average working condition, these working conditions being variable, due principally to the variations in the character of the sandpaper. When the sandpaper is new and sharp it will cut more readily than when old and worn and hence, due to the characteristics of the motor, the drum speed will be somewhat below the average rate, to a possible extent of 15%. When the paper is old and worn, or if it is of particularly fine grain, it will encounter less resistance from the work, with the result that the drum speed may be increased as much as possibly 15% above the average. The characteristics of the apparatus under all worklng conditions, however, are the actuation of abrading element having a relatively small degree of contact with the work under a comparatively light pressure. The degree of contact is limited by the relatively small diameter of the drum and the pressure by the lightness of the entire device. The speed characteristic of the motor, in its variation inversely with respect to the resistance between the work and the drum, acts as a safeguard against the scorching of the wood by the heat of friction. When the sandpaper is sharp and the resistance offered by the wood consequently not great, the drum will be actuated at a speed somewhat below the average without the development of frictional heat 1n an amount dangerous to the wood. As the sandpaper becomes worn, and although there.

is actually more surface rubbing of the wood,

the resistance to the drum is thereby decreased, and the speed of the drum, because of the characteristics of the motor, will be increased above the average.

The high speed motor permits the operation of the fan withdirect connection to the armature shaft, the fan inducing .a very strong and sustained exhaust suction through the exhaust duct, which is effective to handle all of thedust produced by the abrading element. This leaves the abraded surface of the Work perfectlyclearof dust so that its condition maybe minutely inspected, and it keeps theworking parts clear of dust so that there is no danger of their being clogged or disabled from that source. It alsoprevents the at one side of the motor, and thence through the aperture 54L into; the, portion 26* of the Suction; duct 26; A suitable dust bag 74i is arranged to. be attachedto the mouth of the discharge conduit 2% for reception of the dust from-the fan housing;

Nhile thedcvice is adapted particularly forbench werlr it isscapable of use, as a floor sanding? machine by--mea ns-ofr a carriage devic'emhich; is illustrated in, Figs. 9 and 19. This carni-age, device comprises a frame por tion'15 fitted With the angu-larlqr extending handle 76;; of suitable length, and having the dcpendinglugs 77 inwhich are mounted. a rod 78 forming ournals for wheels 79: The frame 75 is. adapted for removable connection tothe bosses 15 of. the base by means of. the screws 80,. forming a-rigid connection between-those? members. The length of the l1-1gs-77'and size of the wheels? 9 are such that when the carriage is so connected to the base, the adjacent end of the-latter will be held siigzhtly. above asur-fa-ce. on which the Wheels rest. By suitable adjustment-of the casing on the base, therefore, the drum may be so positioned that the deviee will be supported on thedrum ancLthe Wheels TQ. By means of the handle 76 theoperator may manipulate the device from a standing position for floor sanding. In this manipulation, the pressure of: the abrading, el-ementupon the floor is constantly under control; of the operator,

7 which .is exercisedby his. supportingmore' or less of theweight ofthe machine through theleverage of the handle 76, The Wheels 79 afford,- a fulcrum support Whereonthe machinemaybe lifted. bvathedepression of the upper end of the handle. The Wheels79rotateindependently, so. thatrthe machine may be.

very. easily: guided It-Willbe observed that the pull of. the drum 's. away fromthe handle 76,..Wl1lfii'l is. an. important factor nfacilitating controlandguidance of the device in its, operation/entire floor surface.

A machine. embodyin my invention. possesses manylfeatures of superior. @iilGiGIlCY. In; the firstblace, by. theem loyment oftlie principles which character my; invention, the machine may, be builti-n very. small size and With-very light weight, both of which characteristics are essential in .a-' bench imachine. The organization of. the apparatus in: such fashion- ,that the abrading' element is driven at a high speedproduces a very rapid eutting, which is rendered practicable by the limitationof the pressure on the abradinp element, andthc limitation of the extent of travel of the abrading element in contact with the work Which is accomplished by the use of a, drum. of relative smalldiameter. As pointed. out. above, the characteristics I of the motorcomperate in attainingthls efncient performance through its compensating response-to increased resistance of the work tothe abra'ding element, whereby a definite hmrtationfis imposedon the development of fricmeaaee tional heat. The suction atthe inlet of the exhaust ductinducesa strong current ofair across the abrading surface, thus exercising a cooling effect on the latter. The employment of a motor of these characteristics,in addition to, the: effectigjust mentioned, permits the Weight of the machine: to be-keptlow' and adapt it for universal; use on: lighting circuits Withoutreqtfring the 'insertion' of special fuse'connectionsahead of it. Another economy is effected in the use. of sandpaperby the employmentlofa: small diameter drumanda high speed operationnvith low pressure,-as azconsiderablygreater surface area may: be sanded with a! materiallyless; area? of. sand paper and in substantially lessstime thanwvith machines operating at the usual slowerspe'eds with heavier pr'essureof the abrad-ing mate;- r-ialon the work.

E claim:

I. A wood surfacing-machine comprising-a be-seportioni,acasingadij ustably mountedom the base portion, and anabrading; drum oper== ably mounted insthe casing, an apronmouni? eda the casing and having. adjustableen ;.ueut withvthe base-member'- i-n- ZEIOIl-t Q-f? the drum, anrex haust duct formed on the casmg and having its inlet betweenthe. drum and theap-son, above the base member, a fan:- opera ably; mounted in; the casi-ni'n -:ommun-ication with the; exhaust duct,'-iamda motel" housed-in therca'sinig for dnivingthe. fa-nmnd drunnr 2.. In a W006i; surfacing machine, in i combrnation', a base member;- a, casing adj ustabl-y mountsd. ORethB, base member for movementtoward: and fromthe same, an abrading drum,

operably mounted in the casing- .and adjust;- able therewith relative/to thev base member, an. adjustable apron extend ingfrom the cas ing-tothebase member infront of thedrum,

an d an air duct formed onthe casing withits;

onv the, casingif'or induction of air near the.

drum, said casing formedr'with a'inoto'ro hous in'g portion and. a, fan. housing, portion, both; in, communication with. the exhaust duct, a. fanj'ine the fair housing, andla motor. in the motor housingfor inducingfa. current of air. through. the moton housing and-exhaust duct;

5. A surfaceismoothingmachine Whose en.-

tire effective Weight does notexceed pending lugsasupported by the carriage for pounds, comprising a frame for support on the surface to be treated, an abrading drum having a diameter of approximately 4 inches mounted in the frame for peripheral engagement with the treated surface, and a motor mounted on the frame and having driving connection with the drum, said motor being modified against standard practice so that when the drum is pressed against the working surface by the weight of the associated structure the drum will be driven at aperipheral speed approximating 3000 feet per minute. u

6. In a surface smoothing machine Whose entire weight does not exceed fifty pounds, the combination of a frame for support on the surface to be treated, a sanding drum of small diameterof about six inches or less operably mounted on theframe for peripheral contact with the treatedsurface, and a motor operably mounted on the frame and having driving connection with the drum, said motor being modified against standard practice so that when the drum is pressed against the working surface by the weight of the associated structure the drum will be driven at a peripheral speed of approximately 3000 feet per minute,

,7. In combination with a surfacing machine, comprising an abrading drum, a driv ing motor therefor, and a frame-carrying saiddrum and motor, of a carriage including a member mounted in overlapped relation to the machine frame, an outwardly extending handle, means for attaching and holding the carriage in its overlapped relation to the machine frame, and a support depending from the carriage for sustaining the adjacent portion of the machine frame in elevated relation to the surface to be treated.

,8. In combination with a surfacing machine, comprising a frame, an abrading drum carried thereby, and means for actuating said drum, of a carriage including a bracket mounted in overlapped relation to the machine frame, an outwardly extending handle associated with the carriage, means for attaching and holding the bracket in its over lapped relation to the machine frame, de-

sustaining the adjacent portion of the machine frame in elevated relation to the surface to be treated, and rollers mounted on said depending lugs for contact with said surface.

9.;'j'In combination with a surfacing machine comprising a frame, provided with a plurality'of upstanding lugs, an abrading drum carried by said frame, and means for actuating said drum, of a carriage including a bracket mounted. in overlapped relation to'the machine frame, and extending over said upstanding lugs, an outwardly extending handle associated with the carriage, fastening devices engaging the said lugs, and serving to attach and hold the carriage bracket in its overlapped relation to the machine frame and supporting means depending from the carriage for sustaining the adjacent portion of the machine frame in elevated relation to the surface to be treated. V V

10. In a wood surfacing machine, the com: bination with a rotary cutting drum, a 1'0? tary motor having a driving shaft, an exhaust fan connected to one end of said shaft, and gearing between said shaft and drum for rotating thesame, of a unitary casing having partitions forming therein a compartment enclosing said drum, a compartment enclosing said motor and said fan, anda compar't ment enclosing said gearing, said drumcompartment having an opening at the bottom thereof to expose a portion of said drumto the working surface, and an exhaust duct connecting said drum compartment with the exhaust space of said fan.

11. In a wood surfacing machine, the combination with a rotary cutting drum, a rotary motor having a driving shaft, an exhaust fan connected to one end of said shaft, and gearing between said shaft and-drum for rotating the same, of a unitarycasing having partitions forming therein a compartment enclos ing said drum, a compartmentenclosing said motorand said fan, a compartment enclosing said gearing, said drum compartment hav ing an opening at the bottom thereof to expose a portion of saiddrum to the working surface, and an exhaust duct connecting said drum compartment with the exhaust space of said fan, said exhaust duct being formed on the surface of said casing and having a common wall therewith.

12. In a wood surfacing machine, the combination with a rotary drum having a cylindrical cutting surface, a rotary driving motor having a shaft extending parallel to said drum, an exhaust fan on said shaft, and gearing connecting said shaft with one end of said drum to rotatethe latter, of a unitary casing having partitions separating the same into a compartment surrounding said motor,ja com= partment surrounding said fan, a comparts ment surrounding said drumyand a compartment surrounding said gearing, said drum compartment havlng an opening for exposmg a portion of said drum toward the working surface, said fan compartment having a central intake chamber communicating with said mctorcompartment' for drawing cooling air therethrough, and an-exhaust duct extending between said drum compartment and said intake chamber, said exhaust duct having an elongated intake nozzle along said drum.

I 13. In a wood surfacing machine, the combination of a drum having a cylindrical cut V ting surface, a rotary motor having adriving shaft, a fan disposed on one end of said shaft, 7 said fan being arranged to exhaust air in the direction from the center to the periphery thereof and havinga central intake space directed toward'said motor, a unitary casing having partitions separating the same into a compartment surrounding said motor, a compartment' surrounding said fan, and a compartment surrounding said drum, said drum compartment'having an opening for exposing a portion of said drum, said fan compartmenthaving a central intake chamber of reduced diameter extending between said fan and said motor, and'an exhaust duetconnectingsaid-drum compartment with said intake chamber-i 14. In'a wood surfacing machine, the combination of a drum having'a cylindricalcutting surface, a'rotary'mot'or having a driving shaft, a fan disposedon one end of'sa-idshaft, said fan-heing' arranged to exhaust air in thedirec'tion' from the center tothe periphery thereof andhaving a central intake directed toward said; motor, a unitary casing having partitions separating the same into a compartment surrounding said motor, a compartment' surrounding said fan, and a compartment surrounding said drum, said drum compartmenthaving an opening for exposing a portion of said drumfsaid fan compartment having acentralintake-chamber of reduced diamet'erextending between said fan and said motor, andan' exhaust duct connecting said drum compartment with said'intake chamber, said ex-hamst'duct being-formed on the walis of said casing'and having common wall por tions therewith.

' 15. In a wood surfacing machine, the combination of a drum having a cylindrical cuttingsurface, a rotaryelectricmotor having a central driving shaft, a fan mounted on said shaft, gearing connecting said shaft with said drum to rotate the latter, a unitary casing having partitions forming a compartment surrounding said drum and a compartment enclosing said motor, a'removable cover on one end of said motor compartment, said cover having a hollow chamber,the gear driving end of said motor shaft extending through said cover wall and terminating in said hollow chamber, the gearing connecting said driving'endwith said drum being housed .and supported in said hollow chamber, andan exl'ia'iist duct extending between said drum compartment and the exhaust portion ofthe compartment surrounding said fan.

16. A; wood surfacing machine comprising a drum having a cylindrical cutting surface. an electricaldriving motor having a central driving shaft extending-parallel to 'said' drum, a unitary, casing constituting a substantially cylindrical chamber surrounding-said motor, and a chamber surrounding saiddrum, said drum chamber being: open at its. bottom for exposing: a; portioniof sai'dtdrum towards the working surface,said; drum chamber and said 111 1 01 chamber having cormnon; wall; portions rye-2,594

and a removablecover for. enclosing the drive ing end of said motor chamber, said cover having a hollow chamber extending transversely tosaid shaft in the direction toward said drum, said shaft terminating within said chamber, and gearing disposed in said chamher for connecting said shaft with said drumsaid gearing comprising supporting shafts journaled in the walls of saidchamber,

17. A wood surfacing machine comprising a drum having a cylindrical cutting surface, a casing having a chamber enclosing said drum, said chamber having an opening at the bottom thereof for exposing a portion of the drum against the working surface, a base plate for guiding said casing with said drum on'sai'd working surface, said base plate having a slot for exposing said drum tot-he working surface, means for vertically adjusting said casing on said base plate to vary the degree of ex posure of the drum through saidsl'ot, and an exhaust duct for removing waste articles incident to the cutting operation o,-- said drum, said exhaust ducthaving an inlet nozzleadjacent said drum above said slot,- the space between the bottom opening of said casing and said slot having an enclosure for confining the suction air current to, the portion of the drum near said slot while permitting vertical adj 11stincnt of said'casing, I

18. A 'wood surfacing machine comprising a drum having a cylindrical cutting surface, an electric motor havinga driving shaft, 7

a unitary casing for said drum and motor having partitions forming therein a chamber enclosing said drum, said chamber having a slot at the bottom thereoffor partially exposing said d'rum,,and a chamber surroundsaid motor and said fan, a base plate for supporting said casing and guiding the same on a working surface, said base plate having a slot through which the exposed portionof the drum may be projected toward the work, means for varyingthe depthofthe projecting portion of the drum extending through said slot, and an exhaust duct extending from said fan for sucking away waste particles-pro duced by the cutting operation of; said drum,- c said duct havingan inlet member adj acent; the. slot in saidbaseplate and arranged to adjusta-bly confine the suction air current to the 'portion of the drum near sai'dslot throughout the range of adjustment of the position of said drum with respect to said base. o

19. A wood surfacing machine comprising a drum having a cylindrical cutting stir-face,- an electri'c motor havi'ng'a drivingshaft, a

unitary casing for said drum and motor havthrough which the exposed portion of the drum may be projected toward the work, a pivotal connection between said casing and said base on one side of said drum to permit tilting of the casing for varying the depth of the projecting portion of the drum extending through said slot, an exhaust duct extending from said fan for sucking away waste particles produced by the cutting portion of said drum, said duct having an inlet nozzle adjacent the slot on the side opposite said pivotal connection, and means for confining the suction a r current to the portion of the drum near said slot throughout the range of the pivotal movement of said casing with respect to said base.

20. The combination with an independently operable wood surfacing machine of the bench type comprising a base plate having a slot, a casing supported on said base'plate, said casing having a cutting drum chamber and a motor chamber, a cutting drum mounted in said drum chamber and having an exposed portion projecting through said slot toward the work, and a driving motor for said drum mounted in said motor chamber, of a detachable carriage for adapting said machine for floor operation comprising a bracket overlapping said base plate and engageable therewith, roller means depending from sa d bracket and extending below the base of said base plate, and a handle extending upwardly back of said roller means whereby said roller means forms a fulcrum whereon said drum may be elevated by depression of said handle.

21. In a wood surfacing machine, the combination with an independently operable cutting unit comprising a drum having a cylindrical cutting surface, a rotary motor for driving said drum, and a casing for operably mounting said drum and said motor, said drum being so associated in said casing as to expose a portion of said drum against the working surface and guide said drum thereon, of a detachable carriage having a bracket member for engagement with said casing, means for detachably securing said bracket member to said casing, roller means depending from said bracket to engage the working surface for permitting said drum to be pivotally swung around said roller means toward and from said working surface, and an upwardly projecting handle extending from said bracket for guiding said carriage and swinging said casing thereon.

22. A wood surfacing machine comprising a drum having a cylindrical cutting surface,

an electric motor for rotating said drum, a

casing having partitions therein forming a compartment surrounding said motor and a compartment surrounding said drum, said drum compartment having an opening at the bottom thereof for exposing a portion thereof toward the working surface, a base plate for guiding said casing and saiddrum, said base having a slot, a pivotal connection be= tween said casing and said base on one side of said drum to permit said drum'to be swung toward and away from saidslot for projecting more or-less of said drum toward said working surface, fan means driven by said motor for producing a suction air current to remove waste particles incident to the cutting operation of said' drum, and "a suction duct leading from said fan means, said suction duct having an inlet nozzle extending into the space between said drum and said baseon the side opposite said pivotal connection.

23. In a wood surfacing machine, the combination with an abrading drum, a rotary motor,',a driving [connection between said drum and said motor for rotating the drum, and an exhaust fan driven by said motor, of a unitary one-piece casing having two tubular chambers, the axes of said chambers being substantially parallel, one of said chambers having mounted therein said operating drum in a direction parallel to its axis, the other of said chambers having mounted therein said rotarymotor with its axis substantially parallel to the axis of said drum, said drum compartment having an opening for exposing a portion of the periphery of said drum to the work surface, the walls of said casing being double over a portion thereof and forming a duct communicatin at one end with said drum chamber and at the other end with the exhaust space of the fan in said motor chamber. I

24. In a wood surfacing machine, the combination with an abrading drum, arotary motor, a driving connection between said drum and said motor for rotating said drum, and an exhaust fan driven by said motor, of a unitary one-piece casing having a compartment for housing said drum, a compartment for housing said motor and a compartment for housing said exhaust fan, said casing being at least in part double walled, the space between said double walls forming a duct one end of I which communicates with said drum compartment and the other end of which communicates with the exhaust space of said fan to constitute an exhaust duct for removing waste particles produced by the action of said drum.

25. The method of operating a surface smoothing machine having a motor driven abrading drum which consists in rotating said drum at a peripheral speed approximating 3000 feet per minute while pressing said drum against the treated surface with a pressure of less than nine pounds per inch of drum length. I 26. The method of operating 'a wood smufacing machine having a sanding drum of a diameter of about six inches or less which consists in utilizing the weight of said machine for applying to said drum the pressure of the order of five pounds per inch drum length while rotating said drum at the peripheral speed of approximately 3000 feet per minute.

27. A surfacing machine comprising a sanding drum of a diameter of about six inches or 'less, a support for s'aid mzichine for guiding the seine over the surface to be treat ed, a motor-mounted on said support and hem ing a driving connection with said drum, the total Weight of said machine being such that said drum is applied against the surface to be treated with a pressure of less than nine pounds per inch drum length, said motor be ing arranged to drive said drum under said pressure against the treated surface at a peripheral speed of the order of 3000 feet per minute.

' In testimony whereof I have hereunto subscribed my name.

' ALEX A. CLARKE. 

